COCCIDIOIDOMYCOSIS (Coccidioides immitis)

Coccidioidomycosis is primarily a pulmonary disease. About 60 % of the infections in the endemic area are asymptomatic.

About 25 % suffer a "flu-like" illness and recoverwithout therapy. This disease exhibits the typical symptoms of

a pulmonary fungal disease: anorexia, weight loss, cough, hemoptysis, and resembles TB. CNS infection with C. immitis is more common while it is less frequent with the other fungal

diseases.

Desert soil, pottery, archaeological middens, cotton, and rodent burrows all harbor C. immitis.

C. immitis is a dimorphic fungus with 2 life cycles. The organism follows the SAPROPHYTIC cycle in the soil and

the PARASITIC cycle in man or animals

Saprophytic cycle starts in the soil with spores (arthroconidia) that develop into mycelium. The mycelium then matures and forms

alternating spores within itself. The arthroconidia are then released, and germinate back into mycelia. The parasitic cycle involves the

inhalation of the arthroconidia by animals which then form spherules filled with endospores. The ambient temperature and

availability of oxygen appear to govern the pathway. The organism can be carried by the wind and therefore spread hundreds of miles in storms so the distribution is quite wide. The spores of the organism

are readily airborne. The cases that occur are usually in patients who have visited an endemic area and brought back pottery, or blankets purchase from a dusty roadside stand, who were exposed when they

were stationed in the endemic area.The cotton, grown in the desert of the Southwest of USA, was

contaminated with the fungus and the mill workers inhaled the spores while handling the raw cotton and developed coccidioidomycosis

Clinical Specimens

Clinical specimens include sputum, pus from skin lesions, gastric washings, CSF, and biopsy material from skin lesions. Mycology C. immitis is a dimorphic fungus. Cultured on SDA at 25 ºC it grows as a

mold in 2 to 3 weeks. Characteristically, the mycelia develop arthroconidia. ("By their fruits ye shall know them"). It is a barrel-shaped (smaller at the edges, wider at the middle) asexual spore.

Typically, the arthroconidia alternate with non spore-forming cells in the mycelium. When grown in vitro at 37º C, there is no yeast form!! C. immitis is a dimorphic fungus; in vivo, (pus or tissue) one sees the

pathogenic or invasive form which is a spherule. The organism develops into spherules (30-60 µ) that are filled with endospores which

are 3 to 5 microns in diameter. A spherule will develop endospores within, then break apart, releasing the endospores. This is the tissue

form seen in pus or histological sections: spherules and loose endospores. They can also be seen in a KOH preparation of sputum. It

is pathognomonic for coccidioidomycosis.

HistopathologyThe inflammatory reaction is both purulent and granulomatous.

Recently releasedendospores incite a polymorphonuclear response. As the

endospores mature intospherules, the acute reaction is replaced by lymphocytes, plasma

cells, epithelioidcells and giant cells.

Serology

There are four tests for diagnosis:•Complement-Fixation (C-F)

•Slide agglutination•Immunodiffusion

•EIAC-F antibody is slow to rise and develop in about 1 month. This test is excellent for coccidioidomycosis because it is quantitative. However, these antibodies cross-react with

some other fungi (Blastomyces and Histoplasma(

The C-F test is also a PROGNOSTIC test. If the titer keeps rising, then the patient is responding poorly and the course may be fatal. If the C-F titer is dropping then the prognosis for that patient is favorable. A titer of greater than 1:128 usually indicates extensive dissemination.

Life-long immunity usually follows infection with C. immitis. There is a much greater mortality rate in dark-skinned people (Mexicans, Filipinos, and Blacks). They are 25 times more likely to develop progressive disease and death. The reason for this is obscure.

TreatmentAmphotericin B, fluconazole and itraconazole are the drugs of choice.